During Phase II of this project, effort will continue toward developing rapid, efficient methods for detecting known polymorphic genetic variants of human cytochrome P450 genes CYP2D6 and CYP2C19. Phase II will specifically demonstrate: (1) the design and synthesis of a single chip capable of detecting 21 polymorphisms that characterize 12 known CYP2D6 genetic variants and 2 known CYP2C19 variants. In addition, the chip will detect 10 polymorphisms that distinguish CYP2D6 from the related, unexpressed pseudogenes CYP2D7 and CYP2D8. Phase I chip designs allowed both resequencing of CYP2D6 and CYP2C19 and characterized 26 polymorphisms. In Phase I assays for coding and non-coding DNA strands were on separate chips. The single Phase II chip array will have probes to interrogate both DNA strands. (2) the refinement of PCR amplification conditions into a multip1ex that permits co-amplification of all sequences required to analyze both genes. (3) the chip genotyping performance using both a collection of characterized genomic DNA samples provided by our collaborator and sequenced genomic clones developed here. Phase II results will provide optimized arrays to conduct Phase III studies which will focus on retrospective and prospective genotyping studies of patients taking drugs metabolized by CYP2D6 and CYP2C19. PROPOSED COMMERCIAL APPLICATION: Important pharmacogenetic effects have been documented for hundreds of drugs accounting for millions of prescriptions annually. These compounds typically have a narrow therapeutic index and cytochrome genotypic analysis is key to their effective therapeutic management. Cytochrome P450 genotyping also provides a tool to help guide therapeutic use of drugs under development. Such genotyping should result in greater efficacy and safety in drug administration.